Re: [PATCH v2 1/2] mfd: dt: tps6586x: Add power off control

From: Stephen Warren <swarren@wwwdotorg.org>
To: Bill Huang <bilhuang@nvidia.com>
Cc: "'Thierry Reding'" <thierry.reding@avionic-design.de>,
	"'sameo@linux.intel.com'" <sameo@linux.intel.com>,
	"'grant.likely@secretlab.ca'" <grant.likely@secretlab.ca>,
	"'rob.herring@calxeda.com'" <rob.herring@calxeda.com>,
	"'rob@landley.net'" <rob@landley.net>,
	"'broonie@opensource.wolfsonmicro.com'" 
	<broonie@opensource.wolfsonmicro.com>,
	Laxman Dewangan <ldewangan@nvidia.com>, Xin Xie <xxie@nvidia.com>,
	"'lrg@slimlogic.co.uk'" <lrg@slimlogic.co.uk>,
	"'jhovold@gmail.com'" <jhovold@gmail.com>,
	"'kyle.manna@fuel7.com'" <kyle.manna@fuel7.com>,
	Rhyland Klein <rklein@nvidia.com>,
	"'devicetree-discuss@lists.ozlabs.org'" 
	<devicetree-discuss@lists.ozlabs.org>,
	"'linux-doc@vger.kernel.org'" <linux-doc@vger.kernel.org>,
	"'linux-kernel@vger.kernel.org'" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 1/2] mfd: dt: tps6586x: Add power off control
Date: Fri, 24 Aug 2012 21:34:26 -0600	[thread overview]
Message-ID: <503847C2.3080400@wwwdotorg.org> (raw)
In-Reply-To: <A7051F87A141B744BCAF487D48E5B3BDF5BA98284B@HKMAIL02.nvidia.com>

On 08/24/2012 06:36 PM, Bill Huang wrote:
>>> On Sun, Aug 19, 2012 at 06:07:55PM -0700, Bill Huang wrote:
>>>> Add DT property "ti,system-power-controller" telling whether or not
>>>> this pmic is in charge of controlling the system power, so the power
>>>> off routine can be hooked up to system call "pm_power_off".
...
>>> I've seen the following while trying this patch applied on top of next-20120817:
>>>
>>> [   40.581151] Power down.
>>> [   41.583160] ------------[ cut here ]------------
>>> [   41.587784] WARNING: at /home/thierry.reding/src/kernel/linux-ipmp.git/drivers/i2c/busses/i2c-
>>> tegra.c:525 tegra_i2c_xfer+0x21c/0x29c()
...
>> Thanks Thierry, I can repro this on Tegra20 inconsistently and found, if current cpu is not cpu0 when
>> doing "machine_shutdown" (it will call "smp_send_stop"), i2c controller will failed to do any
>> transaction (looks like gic interrupt will be disabled), I'll debug further to find out the root cause.
>>
>> By the way, Tegra30 is good since it will always be cpu0 when doing "machine_shutdown", I still don't
>> know why it makes the difference against Tegra20 since I'm not familiar with those cpu stuffs and what
>> make it behave differently, I'll study a bit, thanks.
>
> I've sent the shutdown issue for discussion in ARM list: Shutdown problem in SMP system happened on Tegra20.
> The cause of the i2c timeout is pretty clear now and it is not directly related to this patch, so is this
> patch series acceptable? Any thoughts or comment? Thanks.

I tend to agree; power off never worked without this patch, and
sometimes does with the patch, due to nothing wrong with this patch.

Bill, please do follow up on getting the underlying Tegra issue solved
somehow though. IIRC, Joseph Lo or Prashant has a patch which enabled
the config option that Russell mentioned, so the fix may just be to wait
for that patch to get finalized, but please double-check that solves it.
Thanks!